A sexual act where during oral intercourse the male withdrawals from the woman's (or man's) mouth after ejaculating. The woman then keeps the seamen in her mouth, in the cheek pockets. The man then slaps both cheeks at once and the woman makes a gurgle/trumpet noise as she expels the seamen.
After becoming bored with the angry pirate Koko decided to give her a cumtrumpet. What he did not plan for was the trumpet to be shot at him.
When someone who has recently swallowed semen plays the trumpet; they are then referred to as a Cumtrumpet.
After taking a Risk, Kerry then proceeded to play the trumpet- prompting Stephen to call her a 'cumtrumpet'.